﻿using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Web;

namespace SDLITS.Common
{
    public class CreateImages
    {

        public CreateImages()
        {
            //
            //TODO: 在此处添加构造函数逻辑
            //
        }
        public static void DrawImage()
        {
            CreateImages img = new CreateImages();
            HttpContext.Current.Session["CheckCode"] = img.GetRandomNumberString(4);
            img.CreateImage(HttpContext.Current.Session["CheckCode"].ToString());
        }
        public string GetRandomNumberString(int int_NumberLength)
        {
            string str_Number = string.Empty;
            Random theRandomNumber = new Random();

            for (int int_index = 0; int_index < int_NumberLength; int_index++)
                str_Number += theRandomNumber.Next(10).ToString();

            return str_Number;
        }
        //生成随机颜色
        public Color GetRandomColor()
        {
            Random RandomNum_First = new Random((int)DateTime.Now.Ticks);
            //  对于C#的随机数，没什么好说的
            System.Threading.Thread.Sleep(RandomNum_First.Next(50));
            Random RandomNum_Sencond = new Random((int)DateTime.Now.Ticks);

            //  为了在白色背景上显示，尽量生成深色
            int int_Red = RandomNum_First.Next(256);
            int int_Green = RandomNum_Sencond.Next(256);
            int int_Blue = (int_Red + int_Green > 400) ? 0 : 400 - int_Red - int_Green;
            int_Blue = (int_Blue > 255) ? 255 : int_Blue;

            return Color.FromArgb(int_Red, int_Green, int_Blue);
        }

        /**/
        /// <summary>
        /// 生成图片（增加背景噪音线、前景噪音点）
        /// </summary>
        /// <param name="checkCode">随机出字符串</param>
        public void CreateImage(string str_ValidateCode)
        {
            int int_ImageWidth = str_ValidateCode.Length * 13;
            Random newRandom = new Random();
            //  图高20px
            Bitmap theBitmap = new Bitmap(int_ImageWidth, 20);
            Graphics theGraphics = Graphics.FromImage(theBitmap);
            //  白色背景
            theGraphics.Clear(Color.White);
            //  灰色边框
            theGraphics.DrawRectangle(new Pen(Color.LightGray, 1), 0, 0, int_ImageWidth - 1, 19);

            //  10pt的字体
            Font theFont = new Font("Arial", 10);

            for (int int_index = 0; int_index < str_ValidateCode.Length; int_index++)
            {
                string str_char = str_ValidateCode.Substring(int_index, 1);
                Brush newBrush = new SolidBrush(GetRandomColor());
                Point thePos = new Point(int_index * 13 + 1 + newRandom.Next(3), 1 + newRandom.Next(3));
                theGraphics.DrawString(str_char, theFont, newBrush, thePos);
            }

            //  将生成的图片发回客户端
            MemoryStream ms = new MemoryStream();
            theBitmap.Save(ms, ImageFormat.Png);

            HttpContext.Current.Response.ClearContent(); //需要输出图象信息 要修改HTTP头 
            HttpContext.Current.Response.ContentType = "image/Png";
            HttpContext.Current.Response.BinaryWrite(ms.ToArray());
            theGraphics.Dispose();
            theBitmap.Dispose();
            HttpContext.Current.Response.End();
        }
    }
}